Frank1959

Hello all and thanks in advance. First off please bear with me, I am about as far from being a mechanic as one can be. I can change oil, slap brake pads on, etc. With that said I have a 92 f150 v6 2wd with 120k miles. Love this truck, paid 500 for it 5 years ago and I don't think I've got 500 into it! I use it every day back and forth to work about 20 miles a day and that's about it. Ok I've got no heat. Water pump was replaced about a month ago. I replaced the thermostat when the no heat problem started and immediately after noticed the truck runs ice cold, temp gauge barely reaches the N in normal on gauge and still no heat of course. I can drive her for an hour and gauge never gets anywhere near into normal range ( which I assume is better than running hot) is it possible the new thermostat is faulty? And stuck "open" so antifreeze is just running through the engine keeping it cool and not giving me heat? Any help would be appreciated, I leave for work at 5 am and I live in upstate NY and it's COLD 😀
Thanks again for any suggestions.

wde3477

Welcome to the site!
Are the hoses getting hot? Both heater hoses should be hot and about the same temperature relative to each other.
If the radiator hoses are hot but the heater hoses not, could be blockage in the heater core or a kink in the hoses. Also, ensure that the coolant level is full-up and any air is purged - getting the air out is sometimes a challenge after the cooling system is opened up such as with the water pump replacement.
If the radiator hoses don't get hot, suggest the thermostat is the top likely culprit.
Don't bet the farm on the gauge reading - after 25 years, it may not be entirely accurate...
Good luck, and keep us posted.

Frank1959

Thanks much for the assistance! Ok the upper hose is hot (not screaming hot though) and definitely NOT under any kind of pressure when I squeeze it. Both heater hoses are lukewarm at best, not nearly as hot as the radiator hose. The radiator cap also lukewarm at best and this is all after driving for 45 minutes. I agree the temp gauge is probably not 100% accurate but with that said prior to changing thermostat it always ran pretty much dead center of normal range. Thanks again!

wde3477

Ah, yes, while the gauge may not be entirely accurate, it is typically rather consistent, going to the same place every time for a given temperature.
Re-reading your first post, suggest to keep in mind that if a 2nd new thermostat gets the gauge back to its previous readings, may still have to chase the heater issue - but, first things first.
Double-checking here - are you certain the system is full of coolant? Reason I ask is that the temperature sensor doesn't read air very well.

sdmartin65

Agree with air in system. I had to put our old 4.9 on a steep incline then remove radiator cap and massage lines a bit to work the air out after a water pump replacement. Front needs to be 3 ft or more higher than the back to get it out, at least in my case it did.

JerseyGray

Bad thermostat, not closing

Frank1959

Antifreeze level is good, no problem there, I should've mentioned that I did check that earlier. The truck ran at it's normal operating temp after the water pump change but I'm not sure if I had no heat immediately after that since it was summer and didn't think to check it. The cold operating temp definitely showed itself after the thermostat change...not sure if any of this helps. I really appreciate all the input!

sdmartin65

Always a possibility, but remember one of the reasons Ford stopped using the 4.9 was its length. Won't fit in the newer body styles too long, same reason it'll trap air when opened up.

Chris_1

iTrader: (1)

Thermostat is the most likely issue. Should be a 192 or 195 degree. Don't be afraid to spend a little extra on it for a good brand name.
If your engine is running cold you probably could have bought 20 thermostats (or more) just for the cost of the excess fuel you're burning.